The present invention relates to a method of making a dental prosthesis comprising a reconstruction mass fixed to a metal support and formed essentially of a composite material containing a polymer binder having an inorganic filler dispersed therein, and the invention also relates to a dental prosthesis of this type.
Before describing the invention, it is appropriate to specify the terminology used in the present specification and which corresponds to that of the person skilled in the art.
Care of the teeth comprises essentially the field of repair and reconstruction proper of the teeth, and the field of prosthetic reconstructions. The term “repairs” cover fillings (classes I to V), inlays, and onlays.
Prosthetic reconstructions are prostheses that may be fixed or removable. Usually, such reconstructions have a metal portion and apply to a plurality of teeth, although they can also apply to a single tooth only. They are fixed to one or more teeth. They may also be fixed to one or more implants. Such reconstructions are also referred to as “prostheses” in the present specification.
The invention relates to prosthetic reconstructions of the fixed type. In general, these fixed type reconstructions comprise a metal support made by casting a metal or an alloy, and a reconstruction mass that is fixed to the support and that may be made of various different materials. The materials in most widespread use for such fixed reconstructions are ceramic materials and new-generation composite materials.
The term “new-generation composite material” is used to designate a polymerized composite material having bending strength of not less than 100 megapascals (MPa) and Vickers hardness of not less than 450 newtons per square millimeter (N/mm2). As examples of such materials, mention can be made “Columbus” and “Cristobal” from the supplier IDR.
Ceramic prosthetic reconstructions present great rigidity and low bending strength, and they must be fixed on teeth that are solidly consolidated. From the point of view of preparation, protocols for constructing such ceramic prosthetic reconstructions are simple and well established, and they enable practically all prosthesis technicians to obtain a very high success rate. From the point of view of clinical results, it is found that people fitted with such large-sized ceramic reconstructions often encounter problems in the periodontium (alveolysis) possibly with thickening of the alveolodental ligament, and frequently with more or less pronounced mobility of the teeth and fractures. The failure rate due to the above-mentioned problems is significant.
Prosthetic reconstructions made of new-generation composite materials raise an opposite problem. From the point of view of clinical results, these prosthetic reconstructions give excellent results, as has been proved by numerous clinical trials. From the preparation point of view, although it is known how to make dental prostheses having a reconstruction mass that is constituted essentially out of new-generation composite material, as described in document WO 95/06453, such prosthetic reconstructions raise problems of preparation since it is difficult to fix the reconstruction mass to the metal support. Although experienced prosthetic technicians can obtain excellent results in reproducible manner for such fixing, only about one-tenth of prostheses technicians are capable of reliably achieving the bonding needed for fixing such prostheses. It can thus be considered that making prostheses out of new-generation composite materials suffers from the drawback of requiring highly experienced technicians.